Fabrication and Optical Properties of Strain-free Self-assembled Mesoscopic GaAs Structures

Saimon Filipe Covre Da Silva,Carlos Alberto Ospina Ramirez,Suwit Kiravittaya,Christoph Deneke,Fernando Iikawa,Sidnei Ramis De Araújo,Odilon D D Couto,Thayná Mardegan

doi:10.1186/s11671-016-1782-1

Saimon Filipe Covre Da Silva, Carlos Alberto Ospina Ramirez + Show 6 more

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We use a combined process of Ga-assisted deoxidation and local droplet etching to fabricate unstrained mesoscopic GaAs/AlGaAs structures exhibiting a high shape anisotropy with a length up to 1.2 μm and a width of 150 nm. We demonstrate good controllability over size and morphology of the mesoscopic structures by tuning the growth parameters. Our growth method yields structures, which are coupled to a surrounding quantum well and present unique optical emission features. Microscopic and optical analysis of single structures allows us to demonstrate that single structure emission originates from two different confinement regions, which are spectrally separated and show sharp excitonic lines. Photoluminescence is detected up to room temperature making the structures the ideal candidates for strain-free light emitting/detecting devices.

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Semiconductor quantum dots have been the subject to intensive research in the last three decades and one of the model systems for nanotechnology
We find that a good fit of the mesoscopic GaAs structure (MGS)-S temperature behavior, whereas the quantum well (QW) partly deviates from the expected curve and recovers for higher temperatures
In summary, we demonstrated that by the combination of Ga-assisted deoxidation and local hole etching at room temperature optical active mesoscopic GaAs structures (MGS) with a maximal length up to 1.2 μm × 0.2 μm can be fabricated

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Semiconductor quantum dots have been the subject to intensive research in the last three decades and one of the model systems for nanotechnology. One of the main mechanisms to fabricate these nanometer-sized structures is the Stranski–Krastanov growth mode of epitaxial lattice mismatch materials [1,2,3]. This method has the disadvantage that the obtained quantum dots are inherently strained, which modifies optical and electrical properties of the material [4]. A second tactic is to pattern the substrates with holes and grow a light-emitting structure of AlGaAs/GaAs/AlGaAs on top resulting in a quantum dot at the hole position in the initial template. Strategies for hole fabrication have included the in situ etching of holes [16, 17] and their overgrowth [7], Ga-

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